Audio Copy Protection System

Abstract

An apparatus for applying an anti-copy protection signal for use with switchable head recorders, such as Video Hi-Fi recorders, is described. A high frequency pulsed signal is added to an original signal. The pulses interfere with the compensator circuitry such that the switching of the record head cannot adequately be masked on recording of a signal. On playback, the switching of the recording heads can subsequently be heard. In Video Hi-Fi recorders, the effect of the high frequency signals also interferes with the compressor-expander circuits to worsen the sound of the head switching.

Description

[0001] This invention relates to an audio copy protection system, and in particular to an audio copy protection system for use in a VHS Hi-Fi stereo recording system. [0002] Present day recording technology allows audio and audio-visual signals to be easily recorded onto storage media such as magnetic cassettes, hard disk drives, compact discs, solid state memory devices, DVDs and so on. While this beneficially allows valuable audio and audio-visual data to be backed-up, it can also allow illegal copies of a work to be easily made. An illegal copy may comprise an unauthorised, freely obtained individual copy of an author's work for individual use, or at the other extreme may be one of a large number pirate copies reproduced and distributed to a greater number of people. In either of the two cases, an illegal copy represents lost revenue from the sales of the copyrighted work. For audio-visual content, such as films or movies, pirate copies of the work may have further consequences, ...

AI Technical Summary

Benefits of technology

[0002] Present day recording technology allows audio and audio-visual signals to be easily recorded onto storage media such as magnetic cassettes, hard disk drives, compact discs, solid state memory devices, DVDs and so on. While this beneficially allows valuable audio and audio-visual data to be backed-up, it can also allow illegal copies of a work to be easily made. An illegal copy may comprise an unauthorised, freely obtained individual copy of an author's work for individual use, or at the other extreme may be one of a large number pirate copies reproduced and distributed to a greater number of people. In either of the two cases, an illegal copy represents lost revenue from the sales of the copyrighted work. For audio-visual content, such as films or movies, pirate copies of the work may have further consequences, such as decreasing the revenue from the box office opening of a movie.

[0009] In a preferred embodiment of the invention, there is provided an apparatus for applying an anti-copy protection signal for use with switchable head recorders, such as Video Hi-FI recorders. A high frequency pulsed signal is added to an original signal. The pulses interfere with the compensator circuitry such that the switching of the record head cannot adequately be masked on recording of a signal. On playback, the switching of the recording heads can subsequently be heard. In Video Hi-Fi recorders, the effect of the high frequency signals also interferes with the compressor-expander circuits to worsen the sound of the head switching.

Problems solved by technology

The pulses interfere with the compensator circuitry such that the switching of the record head cannot adequately be masked on recording of a signal.

In Video Hi-Fi recorders, the effect of the high frequency signals also interferes with the compressor-expander circuits to worsen the sound of the head switching.

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